1. Field of the Invention
The present invention relates to a lamp unit to be used in forming a linear portion of a cut-off line in a vehicle headlamp.
2. Description of the Related Art
As described in, e.g., “Patent Document 1,” a conventionally-known vehicle headlamp is structured such that a light distribution pattern having a predetermined cut-off line is formed at an upper end section in a method of scattering reflection control, controlling the light, which is originated from a light source, at the reflector.
Patent Document 2 discloses an optical device structured such that light emitted from a light-emitting chip of a light-emitting diode is once reflected on the front surface of a sealing resin member and then said reflected light is reflected again on the rear surface of the sealing resin member, thereby thus-reflected light is irradiated forwardly from the front surface of the sealing resin member.
[Patent Document 1]                JP-A-2001-351410        
[Patent Document 2]                JP-A-20020-94129        
If the optical device described in Patent Document 2 is used as a lamp unit of a vehicle headlamp, the headlamp unit can be downsized in low profile shape.
However, the outline of the light distribution pattern in Patent Document 2 has such a problem in that said outline formed by the light emitted by the optical device is considerably obscure, whereby this optical device can not be properly used as a lamp unit for forming a cut-off line.
The present invention has been conceived in view of the circumstance and provides with a lamp unit—which affords a low profile configuration and can form a clear cut-off line—as a vehicle headlamp for forming a linear portion of a cut-off line.